Dielectrically loaded waveguide assembly

ABSTRACT

A body of gyromagnetic material closely fitted within a flexible waveguide is supported by means of an external clamp and a pair of dielectric guides.

iliiiie ason et al.

iaies [191 [451 Sept. 18,1973

DIELECTRICALLY LOADED WAVEGUIDE ASSEMBLY lnventors: Robert Jean Mason,Medford;

Norman Richard Landry, Willingboro, both of NJ.

Assignee: RCA Corporation, New York, N.Y.

Filed: Oct. 30, 1972 Appl. No.: 302,183

US. Cl. 333/95 R, 333/24.l, 333/98 R Int. Cl. H015) 3/12, HOlp 1/00Field of Search 333/24.l, 24.2, 95 R,

333/95 A, 98 R, 81 B; 138/108; 174/12 References Cited UNITED STATESPATENTS 5/1958 Weisbaum 333/24.2

3,316,507 4/1967 Heitcr 333/24.2 X 3,408,597 10/1968 3,617,960 11/1971Lavedan, .lr. 333/24.1

I Primary Examiner-Rud0lph V. Rolinec Assistant Examiner-Wm. H. PunterAttorney-Edward .1. Norton et al.

[57] ABSTRACT A body of gyromagnetic material closely fitted within aflexible waveguide is supported by means of an external clamp and a pairof dielectric guides.

8 Claims, 4 Drawing Figures DIELECTRICALLY LOADED WAVEGUIDE ASSEMBLYThis invention relates to a waveguide assembly and more particularly towaveguide structures which inpresence of a D.C. magnetic field and anRF. magnetic field is similar to that in a mechanical gyroscope. Whenthe dielectric body is ferrite or garnet material and is properly biasedsuch such as by a D.C. magnetic field, the waveguide assembly mayprovide the functions of phase shifting, isolating and limiting of radiofrequency signal waves applied to the waveguide section.

The waveguides are conventionally made by extruding, machining, orcasting tubes to a required cross sectional dimension. This dimension isdependent on the frequency and the modes of the propagating wave. Adielectric body of ferrite or garnet material is dimensioned so as toproperly fit within the waveguide. The ferrite or garnet materials aregenerally fragile and have a different thermal expansion coefficientfrom that of thewaveguides. This can cause fracture of these materialsif they are simply bonded to the waveguide. In addition, the garnetmaterials are magnetostrictive. The stresses on the garnet materialcaused by differences in thermal expansion or contractionbetween thegarnet and the waveguide as when these materials and the waveguide arebonded or are otherwise fixed to each other along their length candrastically effect the magnetic field within the garnet. Consequently,changes in the D.C. bias cause unpredictable changes in the amount ofphase shift, for example, efiected by the waveguide section. Althoughferrite material has no appreciable magnetostrictive effect, at certainfrequencies such as at S-band, the remanent level changes ratherdrastically with substantial change in temperature rendering thisferrite material impractical for many applications at S-band. It istherefore desirable that a means be provided by which ferrite and garnetmaterial particularly may be attached to and supported in a waveguidesection such that the forces of magnetostriction and thermal expansionare minimized to prevent fracture of the material or large changes inthe magnetic field.

Briefly, the present invention provides a waveguid assembly, forexample, a rectangular tube of flexible conductive material. A body ofdielectric material having at least a portion of gyromagnetic materialis spaced FIG. 2 is a perspective drawing of an assembled microwavephase shifter with a portion of the waveguide removed for illustration.

FIG. 3 is an end view of the waveguide assembly of FIG. 2.

FIg. 4 is a cross section of the waveguide assembly of FIG. 2 taken inthe 4-4 plane.

Referring to FIG. 1, there is illustrated a dielectric body 10. At thecenter portion of the body 10 is a member 12 of gyromagnetic material.The term gyromagnetic material refers to those materials, both garnetsand ferrites, which exhibit a gyromagnetic effect when a D.C. and an RF.magnetic field are applied thereacross. At either end of the member 12of gyromagnetic material are bonded high dielectric non-magnetictransformer members 11 and 13 to form the total dielectric body 10.These dielectric transformer bodies 11 and 13 act, when the body 10 isplaced within a rectangular waveguide, as matching elements for theinput and output ends of the waveguide assembly.

Referring to FIGS. 2, 3 and 4, the body 10 is placed within a hollowrectangular waveguide 16 such that the body 10 including the dielectrictransformer members 11 and 13 and the center member 12 is centeredbetween the narrow walls 21 and 23 of the waveguide 16 and extendsbetween the broad walls 17 and 19 of the waveguide 16.. The pair ofdielectric transformer bodies 11 and 13 are at the opposite ends of therectangular waveguide 16. The hollow rectangular waveguide 16 is made upof electrically conductive material. The pair of opposing broad walls 17and 19 of the waveguide 16 are separated by a distance which is normallyslightly less than the heighth dimension of the dielectric body 10 whichis gripped between the opposing broad walls 17 and 19 of the waveguide16. The waveguide walls are made of a material of such thickness andelastic properties to allow the body to be placed within the waveguidewith the walls imposing a force on the body 10 which neither exceeds anacceptable value not is less than sufficient to provide a close fit ofthe gyrobetween the opposed broad walls of the rectangular followingdrawings wherein:

FIG. 1 is a perspective view of a dielectric body ineluding agyromagnetic material member and dielectric matching members.

magnetic body 10 between the waveguide walls 17 and 19. The waveguidewalls 17, 19, 21 and 23 are thin enoughto follow the contour of the body10 but yet be fairly rugged. For example, this waveguide 16 can beformed by drawing a tube through a die to a thickness of 0.014 inch. Theparticular material used, for example, may be 606,1 T3 aluminum as soldby Aluminum Co. of America.

A pair of L-shaped members 27 and 29 with interlocking portions 27a,27b, 29a and 29b are fitted to the outside of walls 17, 19, 21 and 23 ofthe waveguide 16 near the dielectric end 13. See detail in FIG. 3. Themembers 27 and 29 are attached to each other by means of a pair ofscrews'31 and 33 extending through members 27 and 29 respectively andbeing tightened against threads 29c and 27c. located in members 29 and27 respectively. As the L-shaped members 27 and 29 are fitted closer bytightening the screws 31 and 33, the broad walls 17 and 19 of the tubeare brought in closer contact with dielectric member 13 of body 10 so asto clamp the dielectric member 13 between the broad walls 17 and 19 atone end of the waveguide 16. Since the member 12 of gyromagneticmaterial is bonded to the dielectric body 13 and dielectric member 11 isbonded to member 12 the whole body 10 is fixed at one end to waveguide16.

Remote from the clamping end of the body 10 at the dielectric member 13is located a pair of dielectric spacers 35 and 37. See FIGS. 2 and 4.These spacers 35 and 37 fit on either side of the gyromagnetic member 12and inside the waveguide 16 in such a way to prevent lateraldisplacement (toward or away from narrow walls 21 and 23) of thegyromagnetic member 12 and body 10 within the waveguide 16. Referring toFIG. 4, the spacers 35 and 37 are configured with small protrusions 35aand 370 which may fit to small holes 41 and 43 in the side walls 23 and21 respectively of the waveguide 16 to thus lock these spacers intoposition. By making these spacers 35 and 37 U-shaped with the free endagainst the body and the middle portion against the narrow waveguidewall, air can flow through the waveguide 16 to permit cooling.

In the operation of the device as a phase shifter, for example, changesin the amount of phase shift for waves propagating along the waveguideassembly can be provided by changing the amount of DC magnetic fieldbias applied in the direction of arrow 14 in Flg. 2. This D.C. magneticfield bias is applied perpendicular to broad wall 17. The DC. magneticfield bias can be achieved by a magnet located above the wall 17 orbelow wall 19 or can be achieved by making the member 12 a toroid. Whenthe member 12 of body 10 is a toroid, a biasing wire, not shown, extendsalong the length of the member 12 within the center of the member 12 anda DC. current pulse is coupled to the wire.

What is claimed is:

l. A waveguide assembly comprising:

a waveguide of flexible conductive material and having a pair ofopposite walls,

a body of dielectric material spaced between the opposed walls of thewaveguide,

an external clamp coupled to the outside of the waveguide near one endof the body and the waveguide so as to force the opposed walls of thewaveguide against a portion of the body and hold the body, and

dielectric means coupled between the waveguide walls and a point alongsaid body remote from the clamping portion for preventing transversemovement of said body within said waveguide but permitting longitudinalmovement of said body.

2. The combination claimed in claim 1 wherein said dielectric meansincludes a pair of dielectric spacers wherein one of said spacers islocated in the region between a third wall of said waveguide and saidbody and the second spacer is located in the region between a fourthwall of said waveguide and said body.

3. The combination claimed in claim 2 wherein said spacer is U-shapedwith the free ends against the body and the middle portion against thewaveguide wall.

4. The combination claimed in claim 3 wherein said spacers include meansfor locking said spacers within said waveguide.

5. The combination claimed in claim 1 wherein said dielectric bodyincludes a portion of gyromagnetic material and a portion ofnon-magnetic dielectric material.

6. The combination claimed in claim 5 wherein said gyromagnetic materialis garnet.

7. The combination claimed in claim 6 wherein only said non-magneticdielectric material portion of said body is clamped between saidwaveguide walls.

8. The combination claimed in claim 1 wherein said waveguide isrectangular and is made of thin walled aluminum tubing, said third andfourth walls being the opposite narrow walls of said waveguide, saidclamp arranged to force the opposite broad walls of said waveguideagainst said body to hold said body.

1. A waveguide assembly comprising: a waveguide of flexible conductivematerial and having a pair of opposite walls, a body of dielectricmaterial spaced between the opposed walls of the waveguide, an externalclamp coupled to the outside of the waveguide near one end of the bodyand the waveguide so as to force the opposed walls of the waveguideagainst a portion of the body and hold the body, and dielectric meanscoupled between the waveguide walls and a point along said body remotefrom the clamping portion for preventing transverse movement of saidbody within said waveguide but permitting longitudinal movement of saidbody.
 2. The combination claimed in claim 1 wherein said dielectricmeans includes a pair of dielectric spacers wherein one of said spacersis located in the region between a third wall of said waveguide and saidbody and the second spacer is located in the region between a fourthwall of said waveguide and said body.
 3. The combination claimed inclaim 2 wherein said spacer is U-shaped with the free ends against thebody and the middle portion against the waveguide wall.
 4. Thecombination claimed in claim 3 wherein said spacers include means forlocking said spacers within said waveguide.
 5. The combination claimedin claim 1 wherein said dielectric body includes a portion ofgyromagnetic material and a portion of non-magnetic dielectric material.6. The combination claimed in claim 5 wherein said gyromagnetic materialis garnet.
 7. The combination claimed in claim 6 wherein only saidnon-magnetic dielectric material portion of said body is clamped betweensaid waveguide walls.
 8. The combination claimed in claim 1 wherein saidwaveguide is rectangular and is made of thin walled aluminum tubing,said third and fourth walls being the opposite narrow walls of saidwaveguide, said clamp arranged to force the opposite broad walls of saidwaveguide against said body to hold said body.